Teachers' beliefs about teaching and learning are constructed over a lifetime of experiences in classrooms. This nine-year longitudinal study examines preservice teachers' initial educational beliefs and the changes in those beliefs over their teacher preparation program and into their first six years of teaching. Analysis of questionnaires, interviews, and surveys from six teachers revealed that they initially believed that students were similar to themselves, that students in the same grade have similar abilities, that teaching was simple, and that teachers function autonomously. Nine years later, they believed that students differ from one another and from themselves, that differentiating instruction is essential but difficult, that teaching is complex, and that teaching is often constrained by outside factors. The data suggested a common progression from initial idealism, to cognitive dissonance, to a search for an authentic teaching persona, to confidence in their new role as teacher, and then to diminished idealism.